Storage area networks (SAN) are high-speed networks for connecting storage and information processor apparatuses (computers) and are widely used nowadays for establishing high-performance servers and handling ever-increasing amounts of data. FC has become a standard for SANs.
Integrated networks that integrate communication between server communication and storage communication are now able to be achieved with high-speed Ethernet (trademark). As a result, Fibre Channel over Ethernet (FCoE) is now known as a technology (standard) for handling FC packets over Ethernet (trademark). FC packets are encapsulated and stored inside packets in FCoE. Hereinbelow, a packet in which a FC packet is stored is referred to as a “FCoE packet.”
In Japanese Laid-open Patent Publication No, 2005-110253, an E-node (FCoE node) connected to the FCoE network (fabric) using FCoE is able to access traditional FC network nodes via a suitable gateway device. As a result, FCoE is very useful when building new integrated networks while still allowing activity with existing assets.
A technology called N-port ID (identification) virtualization (NPIV) is used when connecting a FCoE network to a FC network. NPIV is a technology for virtualizing addresses used in the FC network. A gateway device for supporting NPIV (hereinbelow referred to as a “NPIV gateway device”) is connected to a FC switch device disposed in the FC network and allows a group of E-nodes that communicate through the NPIV device to be seen as one device by the FC switch device. Consequently, the NPIV gateway device is able to connect the FCoE network with the FC network.
FC packets in FCoE packets are transferred to a path that inevitably passes through the FC switch device when the NPIV gateway device is used for connecting the FCoE network and the FC network. As a result, the amount of traffic may become very large in particular in the link that is the path between the NPIV gateway device and the FC switch device connected to that NPIV gateway device. Communication latency may increase and a communication bottleneck may occur in a link with a traffic amount much higher than other links.
The number of storages and servers connected as E-nodes to the FCoE network may also become very large. In contrast, only a portion of all the switch devices are connected directly to the NPIV gateway device in the FCoE network. As a result, it is preferable that unnecessary packets do not collect when transferred to the NPIV gateway device in order to reduce the number of links that may become bottlenecks.